A cool development from Next Limit today - a new version of Maxwell is out, and is free to all 2.x users.
Version 2.7 of the newly updated render suite includes Maxwell Grass. It's a grass generator that lets you put individual blades of grass onto the geometry you select in your scene.
The new grass extension available in Maxwell Render 2.7 allows you to very easily and quickly create different types of grass. The extension is designed to offer you a great amount of randomization and control with many of the parameters also being mappable.
Update: I've released a Maxwell Grass Preset Pack that takes advantage of this new technology, and gives you 17 beautiful presets to easily apply to your scenes. They include all of the necessary materials to go along with them and even have some bonus training videos to go along with them.
There's also a new plugin for ArchiCAD v13, 14 & 15 users that now includes Maxwell Fire out today. Fire is the interactive preview functionality that allows you to see live updates as you manipulate materials and their positioning on your geometry.
I recommend you go get it!